ORA-12545: Connect failed because target host or object does not exist.

I have install Oracle server on a PC. I have configure the Tnsnames, the listener and the SQLnet.ora.

On the server itself, I could do a tnsping and I can connect with SQLPLUS. But when I try to connect to the database via another pc (And I have configure the tnsnames.ora of this pc) I could do a tnsping successfully but when I try to connect via SQLPLUS I received this error message ORA-12545.

Want I'm doing wrong ?

Thank you for your help.